Ab initio shell-model calculation for ^{18}O in a restricted no-core model space

TL;DR

This paper presents an ab initio shell-model calculation for oxygen-18 using a restricted no-core model space, improving the description of low-lying energy levels by refining effective interactions and energies.

Contribution

It introduces a microscopic derivation of two-body effective interactions and minimal refinement of one-body energies within a no-core shell-model framework for ^{18}O.

Findings

Better description of low-lying energy levels in spsdpf space

Improved modeling of many-particle many-hole states

Enhanced agreement with experimental data for certain states

Abstract

We perform an ab initio shell-model calculation for ^{18}O in a restricted no-core model space, microscopically deriving a two-body effective interaction and introducing a minimal refinement of one-body energies in the spsd or spsdpf model space. Low-lying energy levels, except for the experimental 0_{2}^{+} and 2_{3}^{+} states, are better described in the spsdpf space than in the spsd space. The structure of low-lying energy levels is discussed with an emphasis on many-particle many-hole states beyond the four-particle two-hole configuration.